The church is one of the fruits of the New Covenant. It would be impossible for the New Testament church to exist apart from the New Covenant. The New Covenant produces new hearts through the ministry of the Holy Spirit:
2 You yourselves are our letter, written on our hearts, known and read by everyone, 3 revealing that you are a letter of Christ, delivered by us, written not with ink but by the Spirit of the living God, not on stone tablets but on tablets of human hearts (2 Corinthians 3:2-3).
And we all, with unveiled faces reflecting the glory of the Lord, are being transformed into the same image from one degree of glory to another, which is from the Lord, who is the Spirit (2 Corinthians 3:18).
So then, if anyone is in Christ, he is a new creation; what is old has passed away - look, what is new has come! (2 Corinthians 5:17)